<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>块元素</title>
	<style type="text/css">
		body{
			margin: 0px;
		}
		div{
			background-color: gold;
		}

	</style>
</head>
<body>
	<div>
		一个div
	</div>
</body>
</html>